Efficient orange-red electroluminescence of iridium complexes with 1-(2,6-bis(trifluoromethyl) pyridin-4-yl) isoquinoline and 4-(2,6-bis (trifluoromethyl) pyridin-4-yl) quinazoline ligands

Two novel iridium(III) complexes, Ir(tfmpiq)(2)(acac) (tfmpiq = 1-(2,6-bis(trifluoromethyl) pyridin-4-yl) iso-quinoline, acac = acetylacetone) and Ir(tfmpqz)(2)(acac) (tfmpqz = 4-(2,6-bis(trifluoromethyl) pyridin-4-yl) quinazoline), were synthesized and thoroughly investigated. Both complexes emit orange-red photoluminescence with high quantum yields (Ir(tfmpiq)(2)(acac): lambda(max): 587 nm, eta(PL): 42%; Ir(tfmpqz)(2)(acac): lambda(max): 588 nm, eta(PL): 91%). Furthermore, the complex containing quinazoline shows higher electron mobility than that with isoquinoline. The organic light-emitting diodes (OLEDs) with single-or double-emitting layers (EML) were fabricated using two new emitters. The double-EML device using Ir(tfmpqz)(2)(acac) with the structure of ITO (indium-tin-oxide)/MoO3 (molybdenum oxide, 3 nm)/TAPC (di-[4-(N, N-ditolyl-amino)-phenyl] cyclohexane, 50 nm)/Ir(tfmpqz)(2)(acac) (1 wt%): TcTa (4,4', 4-tris(carbazole-9-yl) triphenylamine, 10 nm)/Ir(tfmpqz)(2)(acac) (1 wt%): 2,6DCzPPy (2,6-bis(3-(carbazol-9-yl) phenyl) pyridine, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl) benzene, 50 nm)/LiF (1 nm)/Al (100 nm) displays good electroluminescence performances with a maximum luminance of 96 609 cd m(-2), a maximum current efficiency of 59.09 cd A(-1), a maximum external quantum efficiency of 20.2%, a maximum power efficiency of 53.61 lm W-1, and the efficiency roll-off ratio is mild.